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  for Metal Finishing since 1989
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Pin holes on painted steel tubes

Hello ,

We are painting on steel tubes which are liquid painted using manual spray gun. The surfaces are pretreated with conveyorised spraying system 7 tank process. We are observing certain defects as shown in the [Pinholes/ craters/ cissing] as shown in the attached file. We would like to know what is the root cause for this and the countermeasures for the above.



Regards,

Ganesh Pandit
- RAP, Hosur
2005

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Looks like a better setting on yr manual gun may be what you need; a lower air to paint ratio.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2005

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You may be suffering from either contamination (in the picture it looks a lot like fish eyes but I could be mistaken) or the outermost layer of paint is drying too fast not allowing solvents from within to evaporate... in other words turn down the aircon or increase the humidity.
Hope it helps.

Pedro de Oliveira Martinho
- Alverca, Santarém, Portugal
2005

Hi, I saw the picture you posted, it looks like fish eyes, either from oil in your air line or water, depending on the type of compressor your using, you may want to get a oil and water filter.

Carl Laudansky
sheet metal industry - Canada
2005